CSS gradients let you display smooth transitions between two or more specified colors.
Gradients are CSS elements of the image data type that show a transition between two or more colors. 
These transitions are shown as either linear or radial. Because they are of the image data type, gradients can be used anywhere an image might be.
Gradient in design is the gradual transition between colors. 
This blending results in a visual effect of colors seamlessly fading into each other, creating a sense of depth.

Their are 3 types:

1.Linear Gradient
2.Radial Gradient
3.Conic Gradient

1.Linear Gradient:

To create a linear gradient you must define at least two color stops. 
The linear-gradient() CSS function creates an image consisting of a progressive transition between two or more colors along a straight line.
A linear gradient is a visual effect that gradually transitions between two or more colors along a straight line. It can be used as a background image. 
In a linear gradient, the colors flow in a single direction, for example from left to right, top to bottom, or any angle you choose. A linear gradient with two color stops.

2.Radial Gradient:

A radial gradient is defined by its center.
To create a radial gradient you must also define at least two color stops
A radial gradient is a progressive transition between two or more colors that radiate from a center point in a circular or elliptical shape.
The radial-gradient() CSS function creates an image consisting of a progressive transition between two or more colors that radiate from an origin. Its shape may be a circle or an ellipse.
A radial gradient is a progressive transition of colors that radiate from a center point, forming a circular or elliptical shape.

3.Conic Gradient:

A conic gradient is a gradient with color transitions rotated around a center point.
To create a conic gradient you must define at least two colors.
A conic gradient is specified by indicating a rotation angle, the center of the gradient, and then specifying a list of color-stops. Unlike linear and radial gradients, whose color-stops are placed by specifying a <length> , the color-stops of a conic gradient are specified with an angle.

Questions:

1.What is gradient in CSS?
2.What are the different types of gradients in HTML?
3.What is gradient layout?
4.How many gradients are there in CSS?